Uploading Quicktime Video

When I upload a Quicktime video it goes through a short process and then the file is listed in the Media Library. When I try to preview it in the blog or even go to the Media Library and try to view it, the Quicktime logo comes up with a ? mark in the middle of it and nothing plays. Obviously it’s not seeing it for some reason. Does anyone have any idea what I need to do to make it work? thanks for your help.